Nozzle bodies having an internal conical seat between a cylindrical bore and a nozzle orifice at the apex of that seat and hence along the axis thereof, can be used in a variety of systems. For example, they can be employed as the so-called injection nozzle for internal combustion engines.
Injection nozzles of that type can be provided with valve bodies which themselves are formed from externally conical members on respective spindles and which can sealingly engage the seat. The valve member can have a spherical configuration to engage the seat with line contact.
Regardless of the particular configurations, the valve member and the seat must have a highly exact fit with extremely small tolerances.
Furthermore, they tend to be small as well and must be fabricated with extremely high precision. The nozzle body can extremely have one or more shoulders and/or one or more grooves to allow them to be mounted in place.
In the past, for the precision grinding or polishing of the internal conical seat of the generally cylindrical nozzle, the latter was clamped, e.g. in a chuck, so that, during the grinding or polishing operation, stresses would be applied to the workpiece. The clamping deformation contributed to increased tolerances and, as a consequence, there were difficulties in the precision grinding or polishing of the workpiece. Other techniques required stabilization of the tool and the like to achieve the high precisions and low tolerances which were required.